1. Field of the Invention
This invention relates to fluid nozzles utilized in rock bits.
More particularly, this invention relates to the use of a plastic nozzle for mining bits that utilize air as the fluid to cool the bit during operation.
2. Description of the Prior Art
Replaceable nozzles for rock bits have been within the state of the art for many years. Where the media to cool and clean a rock bit during operation is in a highly erosive liquid form, such as drilling "mud", the nozzles are typically fabricated from tungsten carbide or the like. These replaceable nozzles are retained in a variety of ways which include the following: threading the nozzle within a rock bit body; pinning the nozzle within the body by utilizing one or more dowel pins; retention of the nozzle in a bit body by utilizing a nail or malleable pin that is driven into an annular groove formed between the nozzle body and the rock bit body; and the use of a variety of snap rings to retain the nozzles within the bit body.
Where air is the cooling and cleaning media, the nozzles are subject to less wear and tear during operation. Thus it has been determined that certain types of plastic nozzles will function with air as the cooling fluid.
U.S. Pat. No. 3,971,577 discloses a union device for flexible tubing. The device comprises a body having an inner bore communicating with an enlarged annular opening in a face of the body. A separate annular bushing is secured in the opening with a press fit by means of an external barb on the bushing which opposes removal of the bushing. The bushing has an oppositely directed internal annular barb which engages in the outer surface of the end of a press fitted flexible tube to tightly secure the tube without constricting its inner passageway which communicates with the bore.
The foregoing invention discloses a single circumferential protrusion which is designed to engage the wall of a plastic opening. The bore opening is slightly less in diameter than the barb portion of the circumferential barb on the inner bushing. Since the inner bushing forming the circumferential barb is fabricated from a metal material, the barb will damage the bore opening in the plastic body when the inner bushing is subsequently removed. The inner bushing cannot be subsequently reinserted because the bore opening is now damaged by the annular barb portion on the bushing.
The present invention overcomes the foregoing problem in that the nozzle is fabricated from plastic and a plurality of equidistantly spaced fins radially extend from the nozzle body. Each fin is extended far enough so that they are relatively flexible. Upon insertion of the finned plastic nozzle into its nozzle retention hole, the multiplicity of fins are deflected and "bite" into the walls of the nozzle retention hole. The bore opening of the nozzle body formed in the rock bit is, of course, slightly less in diameter than the diameter of each of the flexible fins of the nozzle body.